Fabrication of magnetic nanostructures using electron beam induced chemical vapour deposition

Finely focused electron beam induced chemical vapour deposition with iron carbonyl gas, Fe(CO)₅, was carried out at room temperature to fabricate desired-shape nanostructures such as dots, rods and rings. The as-formed structures exhibited an amorphous phase containing iron, carbon and oxygen elements in the whole volume and iron oxide nanocrystals existed near their surfaces. A post-deposition heat treatment at about 600 °C resulted in the transformation into a crystalline alpha-iron phase, while their shapes were maintained. The residual magnetic flux density B_r of the as-formed and alpha-iron nanorods was quantitatively measured by electron holography after magnetization, showing that their B_r values were similar to those of iron micro-powders, although the alpha-iron nanorod has a smaller B_r value than the as-formed nanorod.